docs: def get_cpus_by_arch(cls, arch):
          """
          Get all CPUs info by arch
  
          Args:
              arch(str): CPU architecture
  
          Returns:
              lxml.etree.element: CPUs by arch XML
  
          Raises:
              :exc:`~LagoException`: If no such ARCH is found
          """
  
          with open('/usr/share/libvirt/cpu_map.xml', 'r') as cpu_map:
              cpu_xml = ET.parse(cpu_map)
          try:
              return cpu_xml.xpath('/cpus/arch[@name="{0}"]'.format(arch))[0]
          except IndexError:
              raise LagoException('No such arch: {0}'.format(arch))